In signal operations, numerous different modulation methods may be implemented. In certain cases, a modulation scheme may provide modulation in which a change of a signal in a first modulation mode does not affect or does not greatly affect the signal in a second modulation mode. Such a signal may be described as being orthogonal. For example, a signal may be modulated such that both the phase and amplitude of the signal are modulated, the signal amplitude being a first modulation mode and the signal phase being a second modulation mode.
However, conventional modulation of signals does not utilize all possible signal combinations. For example, the symbols utilized in modulation of a signal in amplitude and phase generally is limited to a single amplitude transition. For this reason, the amount of information that may be contained in such a modulated signal is limited.